Morphological variation in the electric organ of the little skate (Leucoraja erinacea) and its possible role in communication during courtship

Morson, Jason M.; Morrissey, John F.

doi:10.1007/s10641-007-9221-x

Cited by 7 publications

(3 citation statements)

References 15 publications

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“…S1) in order to grasp females during copulation. Other examples include variation in electric organs (Morson and Morrissey ), alar, and malar thorns (Luer and Gilbert ; McEachran and Konstantinou ) and the presence of paired, external reproductive organs (claspers) in males (Pratt and Carrier ).…”

Section: Introductionmentioning

confidence: 99%

Sexual dimorphism in sister species of Leucoraja skate and its relationship to reproductive strategy and life history

Martinez

Rohlf

Frisk

2016

Evolution and Development

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Instances of sexual dimorphism occur in a great variety of forms and manifestations. Most skates (Batoidea: Rajoidei) display some level of body shape dimorphism in which the pectoral fins of mature males develop to create a distinct bell-shaped body not found in females. This particular form of dimorphism is present in each of the sister species Leucoraja erinacea and Leucoraja ocellata, but differences between sexes are much greater in the former. In order to understand the nature and potential causes of pectoral dimorphism, we used geometric morphometrics to investigate allometry of fin shape in L. erinacea and L. ocellata and its relationship to the development of reproductive organs, based on previous work on the bonnethead shark, Sphyrna tiburo. We found that allometric trajectories of overall pectoral shape were different in both species of skate, but only L. erinacea varied significantly with respect to endoskeleton development. Male maturation was characterized by a number of sex-specific morphological changes, which appeared concurrently in developmental timing with elongation of cartilage-supported claspers. We suggest that external sexual dimorphism of pectoral fins in skates is a byproduct of skeletal growth needed for clasper development. Further, the magnitude of male shape change appears to be linked to the differential life histories of species. This work reports for the first time that pectoral dimorphism is a persistent feature in rajoid fishes, occurring in varying degrees across several genera. Lastly, our results suggest that pectoral morphology may be useful as a relative indicator of reproductive strategy in some species.

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Section: Introductionmentioning

confidence: 99%

Sexual dimorphism in sister species of Leucoraja skate and its relationship to reproductive strategy and life history

Martinez

Rohlf

Frisk

2016

Evolution and Development

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“…Raia batis possesses papillae at the posterior face (Stuart & Kamp, 1934). In the little skate Leucoraja erinacea papillae are also located at the posterior face (Morson & Morrissey, 2007). In Electrophorus electricus , large numbers of fine papillae with minute rodlets are found at both faces.…”

Section: Discussionmentioning

confidence: 99%

Ontogeny of the electric organ discharge and of the papillae of the electrocytes in the weakly electric fish Campylomormyrus rhynchophorus (Teleostei: Mormyridae)

Korniienko

Tiedemann

Vater

et al. 2020

J of Comparative Neurology

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The electric organ of the mormyrid weakly electric fish, Campylomormyrus rhynchophorus (Boulenger, 1898), undergoes changes in both the electric organ discharge (EOD) and the light and electron microscopic morphology as the fish mature from the juvenile to the adult form. Of particular interest was the appearance of papillae, surface specializations of the uninnervated anterior face of the electrocyte, which have been hypothesized to increase the duration of the EOD. In a 24.5 mm long juvenile the adult electric organ (EO) was not yet functional, and the electrocytes lacked papillae. A 40 mm long juvenile, which produced a short biphasic EOD of 1.3 ms duration, shows small papillae (average area 136 μm2). In contrast, the EOD of a 79 mm long juvenile was triphasic. The large increase in duration of the EOD to 23.2 ms was accompanied by a small change in size of the papillae (average area 159 μm2). Similarly, a 150 mm long adult produced a triphasic EOD of comparable duration to the younger stage (24.7 ms) but featured a prominent increase in size of the papillae (average area 402 μm2). Thus, there was no linear correlation between EOD duration and papillary size. The most prominent ultrastructural change was at the level of the myofilaments, which regularly extended into the papillae, only in the oldest specimen—probably serving a supporting function. Physiological mechanisms, like gene expression levels, as demonstrated in some Campylomormyrus species, might be more important concerning the duration of the EOD.

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“…As well as overall size, sexual dimorphism in chondrichthyans has been reported in some other characteristics, including the electric organ of some skates (e.g. Morson & Morrissey, 2007) and the snout size of Harriotta raleighana (Finucci et al, 2016b). A previous proposal for a chondrichthyan lek system was challenged on account of a variety of factors, including confirmation of multiple paternity in a single litter (eliminating female mate choice) (Domeier & Nasby-Lucas, 2013).…”

Section: Adult Males Associated With Other Adult Malesmentioning

confidence: 99%

Ecology of New Zealand Deep-sea Chondrichthyans

Finucci¹

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<p>Deep-sea chondrichthyans represent nearly half of the known species of sharks, rays, and chimaeras. Most are poorly known, largely due to their historically low economic value, and thus, low prioritization for research efforts and targeted sampling. Globally, many deep-sea fisheries have proven to be unsustainable, as deep-sea species are generally characterised with life history traits, resulting in low biological productivity. Although generally not targeted, there is a lack of data on New Zealand deep-sea chondrichthyans, despite regularly occurring as bycatch, with no mitigation in place to limit catches. This thesis described aspects of life histories for data deficient deep-sea chondrichthyans caught as bycatch in New Zealand deep-sea fisheries. In Chapter II, research trawl survey data were used to describe and evaluate length-weight relationships, which were found to greatly differ from parameters reported by FishBase. This was followed by the application of a set of models to detect changes in weight at length relationships, and assess if these changes correspond to biological or ecological events, such as length-at-maturity or ontogenetic changes in diet. Chapter III evaluates deep-sea chondrichthyan aggregations and social associations. Not all species were found to engage in aggregative behaviour, but those that did suggested patterns of sex- and size-specific associations which varied with catch density. Adult females were caught most frequently in low densities and were highly associated with other adult females, adult males consistently highly associated with each other, and the highest density catches were dominated by juvenile individuals. These trends may be driven by factors such as foraging, predator avoidance or sexual conflict avoidance. Chapters IV, V, and VI examine, respectively, details of the reproduction, life history, and diet of prickly dogfish (Oxynotus bruniensis), longnose spookfish (Harriotta raleighana) and Pacific spookfish (Rhinochimaera pacifica), and brown chimaera (Chimaera carophila) and black ghost shark (Hydrolagus homonycteris). All species were found to have life histories characteristic of low productivity, including reaching maturation at a large proportion of their maximum length, and having low fecundity. Additional novel biological results included: DNA identification of prey revealed that O. bruniensis preyed exclusively on the egg capsules of holocephalans, potentially making it the only known elasmobranch with a diet reliant solely upon other chondrichthyans; sperm storage was confirmed in female H. raleighana, R. pacifica, and C. carophila; and sexual dimorphism in snout length was found in H. raleighana, where male relative snout size increased at sexual maturity, suggesting that the snout is a secondary sexual characteristic. The depth range of most New Zealand deep-sea chondrichthyans may provide some refuge from current fishing activity. However, results from this thesis have suggested that the species examined here have life histories characteristic of low productivity, and engage in behaviours that will have implications for selective mortality by spatially or temporally stratified fishing. Oxynotus bruniensis, in particular, is likely at higher risk from the impact of fishing than currently estimated, given its reproductive characteristics, highly specialised diet, and distribution overlap with deep-sea fisheries. Continued monitoring and a greater collection of biological data from additional and alternative sources (e.g. fisheries observer program, local fishers, underwater vehicles and video) is recommended to fully understand and negate mortality from human activities.</p>

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Morphological variation in the electric organ of the little skate (Leucoraja erinacea) and its possible role in communication during courtship

Cited by 7 publications

References 15 publications

Sexual dimorphism in sister species of Leucoraja skate and its relationship to reproductive strategy and life history

Sexual dimorphism in sister species of Leucoraja skate and its relationship to reproductive strategy and life history

Ontogeny of the electric organ discharge and of the papillae of the electrocytes in the weakly electric fish Campylomormyrus rhynchophorus (Teleostei: Mormyridae)

Ecology of New Zealand Deep-sea Chondrichthyans

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